CVE-2026-76262 Overview
CVE-2026-76262 is an information disclosure vulnerability affecting Splunk Enterprise 10.4 versions below 10.4.2. An unauthenticated remote attacker can read Prometheus service metrics from the Edge Processor SPL2 Preview sidecar. The exposed data includes runtime and build metadata for the sidecar component. The vulnerability exists because the Prometheus metrics endpoint lacks authentication, allowing any client with network reachability to retrieve metrics without credentials. Splunk Enterprise versions below 10.4 are not affected. The issue is tracked under [CWE-200] Exposure of Sensitive Information to an Unauthorized Actor.
Critical Impact
Unauthenticated network-accessible attackers can harvest runtime and build metadata from the Edge Processor SPL2 Preview sidecar, enabling reconnaissance against Splunk Enterprise deployments.
Affected Products
- Splunk Enterprise 10.4.0
- Splunk Enterprise 10.4.1
- Edge Processor SPL2 Preview sidecar component
Discovery Timeline
- 2026-08-19 - CVE-2026-76262 published to NVD
- 2026-08-20 - Last updated in NVD database
Technical Details for CVE-2026-76262
Vulnerability Analysis
The vulnerability resides in the Edge Processor SPL2 Preview sidecar shipped with Splunk Enterprise 10.4. Splunk sidecars are auxiliary processes that extend Splunk Enterprise functionality for features such as Edge Processor pipelines. The sidecar exposes a Prometheus-compatible metrics endpoint for observability purposes. This endpoint returns time-series metrics describing internal operation, request counters, resource utilization, and build metadata.
The endpoint accepts requests without any authentication challenge. Any network client that can route to the sidecar port receives a full metrics response. Attackers can use the disclosed build strings and runtime data to fingerprint the exact sidecar version, identify feature flags, and correlate metrics with known vulnerabilities in dependent libraries. This reconnaissance can accelerate follow-on attacks against the broader Splunk deployment.
Root Cause
The root cause is a missing authentication control on the Prometheus metrics HTTP endpoint of the Edge Processor SPL2 Preview sidecar. Prometheus scrape endpoints typically expose sensitive operational telemetry and require network-level segmentation or explicit authentication. The affected sidecar was shipped without either enforcement, so requests to the metrics path succeed regardless of caller identity.
Attack Vector
Exploitation requires only network reachability to the sidecar's metrics port. An attacker sends an HTTP GET request to the Prometheus metrics path. The sidecar responds with the full metrics payload, including build and runtime metadata fields. No user interaction, credentials, or prior foothold are needed. The attack can be performed by any actor on the same network segment or by remote attackers when the sidecar port is inadvertently exposed to untrusted networks.
Refer to the Splunk Security Advisory SVD-2026-0801 for vendor technical details.
Detection Methods for CVE-2026-76262
Indicators of Compromise
- Unauthenticated HTTP GET requests to the Prometheus /metrics path on Edge Processor SPL2 Preview sidecar ports
- Access log entries showing metric scrapes from source IPs that are not part of an authorized monitoring infrastructure
- Repeated or scripted enumeration of sidecar endpoints from external or lateral network segments
Detection Strategies
- Inspect sidecar HTTP access logs for requests to /metrics originating outside the approved Prometheus scraper allowlist
- Enable network flow logging on hosts running the Edge Processor SPL2 Preview sidecar and alert on inbound connections from non-monitoring subnets
- Baseline expected scrape frequency and volume, then flag anomalous burst reads of the metrics endpoint
Monitoring Recommendations
- Forward sidecar HTTP request logs to a central SIEM and build a rule for unauthenticated access to the Prometheus endpoint
- Monitor for reconnaissance patterns such as sequential probing of sidecar ports across Splunk indexers and forwarders
- Track deployed Splunk Enterprise versions across the estate and alert on any host still running 10.4.0 or 10.4.1
How to Mitigate CVE-2026-76262
Immediate Actions Required
- Upgrade Splunk Enterprise to version 10.4.2 or later per vendor guidance
- Restrict network access to Edge Processor SPL2 Preview sidecar ports using host firewalls or network access control lists
- Audit exposed sidecar endpoints across the environment and confirm none are reachable from untrusted networks
Patch Information
Splunk has released Splunk Enterprise 10.4.2, which remediates the missing authentication on the Edge Processor SPL2 Preview sidecar Prometheus metrics endpoint. Consult the Splunk Security Advisory SVD-2026-0801 for full upgrade instructions and version guidance. Deployments running Splunk Enterprise below 10.4 are not affected and do not require patching for this issue.
Workarounds
- Apply network segmentation so only authorized Prometheus scrapers can reach the sidecar metrics port
- Deploy an authenticating reverse proxy in front of the sidecar metrics endpoint until upgrading to 10.4.2
- Disable the Edge Processor SPL2 Preview sidecar in environments where the feature is not required
# Example iptables rule restricting access to the sidecar metrics port
# Replace <PROM_SCRAPER_IP> and <METRICS_PORT> with environment-specific values
iptables -A INPUT -p tcp --dport <METRICS_PORT> -s <PROM_SCRAPER_IP> -j ACCEPT
iptables -A INPUT -p tcp --dport <METRICS_PORT> -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
